Silver halide light sensitive photographic materials for use in medical diagnosis are conventionally developed using, as a developing agent, dihydroxybenzenes such as hydroquinone. In a developer containing the dihydroxybenzenes, however, a preservative such as sulfites must be included to maintain storage stability, and it is undesirable in terms of worker's safety. There is also a disadvantage such that the developer causes color change upon aerial oxidation, leading to color staining.
There is known a technique of using reductones as a developing agent in place of the dihydroxybenzenes. The reductones cause no color stain due to oxidation, and ascorbic acid or erythorbic acid is generally employed as a food additive, having advantages such that it is safe for living organisms.
However, a developer containing reductones is easily oxidized under alkaline conditions and is hydrolyzed to give off an acid, which lowers the pH of the developer and disadvantageously results in large variations in processed photographic materials.
Since 1995, open sea disposal of photographic processing effluent has been prohibited, resulting in effluent being incinerated. Such a land-based treatment of the processing effluent results in a rise in energy and cost. Further, the processing effluent itself is limited so that reduction of a replenishing rate is desired. However, the reduction of the replenishing rate prolongs the time of the processing solution in a processing bath, causes oxidative exhaustion of processing solutions, and lowers the density or contrast of processed photographic materials, leading to deterioration of processing stability.
In terms of emergent medical treatment, rapid access to image information is required to quickly diagnose the patient's state and prompt treatment so that rapid processing of photographic material is strongly desired.
As a means for meeting these desires is a technique known of increasing covering power of developed silver to reduce the silver coating amount by means of, e.g., decreasing the average grain size or using tabular grains with a high aspect ratio and small grain thickness. However, such grains capable of providing high covering power tend to produce yellowish developed silver images, leading to deteriorated silver image tone. This is due to the fact that the developed silver decreases in size and thickness with a decrease of the grain size and thickness, resulting in increased scattering of blue light.
As another means for responding to the desire for rapid processing is a technique known of incorporating a dextran into the binder. However, it has the problem of incorporation of the dextran which deteriorates silver image tone. To improve deterioration of the silver image tone, there is known a technique of incorporating a dye capable of remaining in a photographic material after processing. In this case, however, unnecessary dye remains in unexposed portions, resulting in deterioration in residual color. There is further a technique in which a support is previously tinted with a blue dye. Taking account of deterioration of diagnosis due to an increase of fog density, in this case, it is impossible to tint to an extent sufficient for improving silver image tone. In view the foregoing, further means for solving these problems are desired. Furthermore, medical diagnostic photographs are obligated to be retained over a long period of time (at least five years) from requirements to observe the course of disease so that storage stability without image deterioration over a long period of time is essential.